In order to compare the experimental panorama with the predictions of a benchmark axion model, the figures will also show the expectations for the coupling values within the \(Z_{\cal N}\) -KSVZ axion model
developed in Ref. [1]}.
The canonical KSVZ QCD axion solution (i.e. \({\cal N}=1\) ) is shown as
a thick yellow line,
embedded into a faded band encompassing
the model dependency of the KSVZ axion [2]}, [3]}.
Oblique orange lines will signal instead the center of the displaced yellow band that corresponds to solving the strong CP problem with other values of \({\cal N}\) , that is, for a \(Z_{\cal N}\)  reduced-mass axion, see Eq. (REF ).
